Debian

Debian is a preferred Linux release, that is used mainly on desktop computers, but many people have begun using it lately as a web server Operating System as well, because of the stability and security it provides. The latter is a direct result the fact that Debian is developed and supported by countless qualified volunteers around the globe, so that any patch which is needed to fix a certain issue is released within a few days. The very same community will also help you with any question or problem that a user may ever encounter, because they can be contacted through email using e-mail lists and a qualified response will be sent in around 15-20 minutes. The advantage here is that all your questions will be answered by the same people who have created the Operating System itself and they have a detailed knowledge of how it works. As Debian is absolutely free, you will not have to pay any license fees to use it and you'll be able to customize it as much as you want or need. This is valid for the Operating System and the 30.000+ software packages that are readily available for it.